Technical Abstract:
Dollar spot, caused by Sclerotinia homoeocarpa, is one of the most economically important diseases of amenity turfgrasses worldwide. In spite of this, very little is known about the interactions between S. homoeocarpa and its hosts at the molecular level. In the present research, germin-like protein (GLP) family genes were evaluated for their role in defense against S. homoeocarpa. A growth chamber assay was conducted on three creeping bentgrass cultivars with varying levels of susceptibility to dollar spot. Pots of each cultivar were inoculated with either 4 day-old plugs of S. homoeocarpa or plugs of PDA and arranged in a 2x3 factorial within an RCBD with four replications. Tissue for RNA extraction and RT-qPCR analysis was harvested from the site of inoculation at 0, 24, and 96 hpi. Results from RT-qPCR analysis indicated that all GLP genes investigated were significantly up-regulated in inoculated versus mock-inoculated plants at 96 hpi, regardless of host cultivar, but were not up-regulated at 24 hpi. Interestingly, a gene with strong similarity to rice and barley host defense genes was constitutively expressed a slightly higher level in the most resistant cultivar. Silencing techniques are now being employed to investigate the specific role of GLP genes in defense against S. homoeocarpa. This research will be useful for understanding molecular aspects of host defense against S. homoeocarpa and breeding for dollar spot resistance.